1. Field of the Invention
The present invention is directed to a method for producing a thermoplastic composition by melt blending carpet without separating it into its various components. More specifically, the present invention is directed to a method for producing a useful thermoplastic composition from used carpet as well as thermoplastic composition produced by the subject process.
2. Description of the Prior Art
For many years, disposal of waste materials has been conducted in ways detrimental to the environment. It has been burned in massive incinerators thereby polluting the air. It has been dumped into the ocean thereby contaminating the water supply. It has been buried in landfills where it collects without decomposing for years.
In recent times, individuals and corporations alike have expended significant effort on identifying environmentally responsible methods for disposing of waste products constructed from synthetic materials such as resins and plastics. One important direction taken along this line is the development of programs for collecting the synthetic materials for recycling and re-use in other products.
Many useful products, including flooring materials, are currently manufactured from a number of different synthetic materials which have varying physical and chemical characteristics. For example, conventional nylon carpeting includes three primary components: a plurality of tufts formed from nylon, at least one backing formed from a polyolefin such as polypropylene and an adhesive material of styrene-butadiene rubber (SBR) applied as a latex and typically filled with an inorganic filler such as calcium carbonate. Similarly, conventional polyester carpeting includes three primary components: a plurality of tufts formed from a polyester, for example polyethylene terephthalate or a copolymer thereof; at least one backing formed from a polyolefin, for example polypropylene; and an adhesive material, for example styrene-butadiene rubber (SBR) applied as a latex and typically filled with an inorganic filler such as calcium carbonate. Also, conventional polypropylene carpeting includes three primary components: a plurality of tufts formed from polypropylene; at least one backing formed from a polyolefin, for example polypropylene; and an adhesive material, for example styrene-butadiene rubber (SBR) applied as a latex and typically filled with an inorganic filler such as calcium carbonate. These products present particularly difficult challenges to recycling efforts because of the varying chemical and physical characteristics of their individual components in their different forms.
The success of attempts to recycle such multi-component products has been severely limited. For example, U.S. Pat. Nos. 4,158,646 and 5,145,617 disclose methods for reprocessing fiber-containing waste materials wherein the process results in a fiber-containing final product. These type of processes are restricted in utility to the limited application where composite (fiber/matrix) materials are useful.
Still other processes focus on separating out the individual components. Specifically, efforts in reclaiming or recycling carpet materials, such as that disclosed in U.S. Pat. Nos. 4,028,159 and 5,169,870, involve separating the individual materials through various processing steps and recovering the material for reuse. These methods, while effective in reclaiming individual synthetic materials, are extremely expensive to the extent of often being cost prohibitive. Further, the additional energy required to effect the necessary processing steps at least partially reduces the environmental advantage of recycling or reclaiming.
A need therefore exists for a method for processing used carpet into a useful material without the disadvantages described above.